1. Field of the Invention
The present invention generally relates to adjusting devices for phase shifter of antenna and, particularly, relates to an adjusting device for phase shifter of antenna in mobile communication.
2. Description of Related Art
It is well known in the art that base station antenna in mobile communication commonly needs to be tilted downwardly with respect to the horizontal plane. Radiation effect of the base station can be improved via adjusting down-tilt angle of the antenna. At present, down-tilt angle adjustment of base station antenna can be realized via tilting the base station antenna downwardly to form a mechanical down-tilt angle in installation, or via changing phases of different radiation oscillators of the base station antenna and urging beam directions of the base station antenna to bias downwardly to form electrical down-tilt angle.
Mechanical down-tilt angle of the base station antenna may potentially induce deformation of the antenna pattern and, therefore, affect coverage area and disturb of the net. Generally, the mechanical down-tilt angle is restricted in a certain angle range. The electrical down-tilt angle is obtained via changing phases of different radiation oscillators of the antenna and urging beam directions thereof to bias downwardly. Consequently, each lobe almost has same decrease amplitude and, thus, shortcomings of the mechanical down-tilt angle are avoided. The electrical down-tilt angle is generally adjusted via a phase shifter.
As well known in the art, phase shifter is normally set in a protecting shell of the base station antenna. Control device adapted for adjusting the down-tilt angle of the base station antenna is disposed at out side of the protecting shell. Thus, a transmission device is needed to couple the control device to the phase shifter, so as to precisely transfer operating instruction of the control device to the phase shifter situated in the base station antenna and adjust the phase correspondingly.
In conventional design, a slider mechanism similar device is commonly used to actuate the phase shifter. Since the slider mechanism can not linearly transform linear displacement of the control device to angular displacement of the phase shifter, the phase of the phase shifter cannot be adjusted precisely. On the other hand, the mechanical route of the slider mechanism is introduced to the external control device and the mechanical route is controlled via an electronic switch. Therefore, internal structure of the control device needs to be modified in accordance with different mechanical route of the phase shifter, which inevitably limits versatility of the control device.